Hard Disk Considerations

Today’s computers juggle floods of data as we ask them to respond to our creative urges in real time and create DVDs while we wait. High performance AV media drives are pivotal components. If you haven’t considered upgrading your media storage recently, maybe it’s time. Whether you need to add more hard drive space to your current system or are looking to buy that new dream editing suite, you’ll need the answers to the following common questions.

How Much Space Do I Really Need?

A conventional rule-of-thumb is to allow 14 Gigabytes of disk space for each hour of Mini DV video (at 25Mbps). You might expect that a 30-Gig drive would be more than enough for a one-hour project, but you’d be wrong. Your computer’s O/S, editing software, graphics programs and sound editing programs all use space. They also create fleeting, but enormous temporary disk files. You’ll also store music, sound effects, stock footage, titles, special effects and other project elements.

Depending on your editing and shooting style, you can easily capture more than one-hour’s worth of raw footage for each hour of a final production. Well-coordinated and planned shoots with detailed shot logs can minimize the amount of wasted footage. Careful utilization of batch capture utilities can also minimize space requirements. A very rough estimate is that fastidious editors who carefully log and capture only what is necessary will need about 30GB for an hour long project. Most of us will need a bit more. And some of us lazy types who roll the tape, hit the capture button and then rely on scene detection to break up the entire tape will need considerably more. Multiple camera shoots also dramatically increase disk requirements. A one-hour, three-camera music concert or wedding shoot can generate 35 to 45 Gigs of raw video. And what if you have to simultaneously juggle multiple projects?

Finally, rendered projects require space. If you can playback your projects from the timeline, space isn’t as important. But if you need to render to a file, you must include that in your space calculations. For example, the relatively small MPEG-2 files created for a one-hour DVD can consume four Gigabytes or more.

Can I fit everything on one drive?

While it is possible to cram everything onto one drive, multiple drives are highly recommended. Reserve one for your operating system (OS) and software and another for your media files. A capable and economical editing system might have a 20GB drive for your OS and programs and an 80GB drive just for video and other media. You might want a fast drive for your OS (and it would make a difference in your system’s performance), but make sure your media drive is fast. At the time of writing, drive capacities were continuing to expand above 180GB.

Which disk speed specifications are the most meaningful?

Speed is specified in a variety of sometimes confusing ways. Rotational speed, buffer size, seek times and maximum (burst) transfer rates are all technically important, but sustained throughput or minimum transfer rate is the key. You need to marry fast drives to your computer using equally fast connections to get maximum performance.

Minimum acceptable sustained transfer rates vary and specific numbers are hard to come by. Some vendors, like Canopus, offer free disk speed test software you can use to evaluate your computer’s video readiness. You might need anywhere from 3.5 MB/s for DV to 12 MB/s for analog capture (or more). Of course you don’t want to take any risks: we’d be quite nervous about the reliability of a drive that can only sustain 4 MB/s. Moreover, drives slow down as they fill up, sometimes stumbling unacceptably. Unless you really enjoy these technicalities, very broadly speaking, we’ve found that 7,200RPM drives tend to be sufficient for DV editing. If you need to capture analog video to MJPEG you will need to be more careful in your selection. And if you are going to capture uncompressed video, make sure you know exactly what you are doing or consult someone who does. Finally, don’t assume that a 15,000RPM drive will be the best for video: these drives may be extremely fast, but they aren’t generally designed for video.

Should I buy IDE or SCSI drives?

The two disk technologies in common use by videographers these days are Integrated Device Electronics (IDE) and Small Computer Systems Interface (SCSI), pronounced "scuzzy."

Early IDE drives (circa 1996) were slow and serious enthusiasts chose more expensive and capable SCSI drives. Recent IDE design improvements have led to fast, cheap drives that are very capable, largely nullifying the SCSI vs. IDE debate. ATA, UDMA, or EIDE are all modern variations on IDE that you should look for. SCSI drives still have a few advantages (that come at a price), perhaps longer warranties and the ability to chain more than four drives (although the newest Serial ATA standard changes that). Finally, exercise more caution when considering external storage interfaces such as FireWire or USB 2.0 (don’t even consider USB 1.0). External solutions are rarely as reliable as IDE or SCSI.

What are RAID arrays, and do I need one?

There are two paths to high transfer rates: You can buy one really fast drive or purchase multiple relatively slow drives, then connect them in a RAID array, where they share the workload. Of the available variations (RAID 0, RAID 1 and RAID 5), videographers normally choose RAID 0 "striping" arrays for higher sustainable throughput. A RAID is created when multiple drives are connected together via some type of controller. It is increasingly common to find this controller right on your motherboard, but some type of add-on card is often necessary. The drives used to construct the array might be either SCSI or EIDE drives. Building and formatting your own RAID is not terribly difficult, but is also not nearly as simple as popping a new hard disk into your case (which is very easy indeed). Fortunately, excellent pre-build RAID solutions that have been optimized for video are available from companies like Medea.

Internal, External or Removable?

Internal drives are the most conventional, but you might consider locating your media drive(s) in an external housing. Hard disks get hot and draw considerable power. Few consumer-grade computers have adequate cooling fans or power supplies for big media drives. This is one reason why RAIDs are almost always constructed outside of the computer’s case. SCSI solutions can also often extend outside of the case. Newer FireWire and USB 2.0 external drives are portable and convenient. Removable drives, which are internal drive bays that can be easily popped in and out of the front of the computer, are another option and are great for systems used by multiple operators, in three-shift facilities, classrooms or when you have multiple projects.

If all of this seems too complex, you can relax a bit. Five years ago, finding a decent hard drive for video could be a frustrating and expensive experience. Today you can find DV- capable drives on the shelves in any computer store.

[Sidebar: Fine-tuning Hard Drive Performance]

Put your operating system and programs on their own hard disk. Use separate hard disks for media files.

  • Delete old media and temp files after finishing projects.
  • Defragment your drive.
  • Enable write cache in the disk’s Properties boxes (in the Device Manager in Windows). Caching can improve performance.
  • If you can isolate your editing computer from e-mail, the internet and other virus sources, consider running the system without antivirus software.

    [Sidebar: Can I mix drives of different types?]

    "The nice thing about standards," engineers joke, "is that there are so many of them." Whether adding a hard disk to an existing system or specifying components for your dream system, remember that disk drives come in a variety of connector and interface styles. Some SCSI drives have 50-pin connectors; others have 68 or 80 pins, and there is a variety of electrical specifications (e.g. LVD and U2W). These affect cable, disk tray and interface electronic purchasing decisions. Moreover, you can have problems mixing different drive types on the same disk controller. For example, connecting LVD and SE style devices to the same cable will degrade performance. Obviously, if your motherboard does not have on-board SCSI or EIDE capability, you will need to purchase an appropriate interface card or buy a new motherboard.

    [Sidebar: What’s Ahead?]

    Smaller, faster and cheaper, of course. The latest USB 2.0 and FireWire drives make adding and moving drives quick and easy. Both approaches let you plug and unplug external drives, and transfer video at impressive speeds. Most new computers come with FireWire and USB 2.0 ports built in. You can add these ports to many existing computers.

    Perhaps the most intriguing new designs, however, let you connect portable hard disks to the FireWire port on your camcorder. You record video directly to disk as you shoot, then plug the drive into your editing computer, eliminating the need to transfer the footage from tape to disk. Sony professional systems are moving in this direction. In the consumer space, products like the Focus FireStore, while expensive, are worth a look.

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